New technologies remain to expand options for treating keratoconus, myopia, hyperopia

Arising modern technology in the areas of corneal ring sectors, holmium laser thermokeratoplasty (LTK) and phakic IOLs is giving brand-new choices for people dealing with keratoconus, nearsightedness, hyperopia as well as presbyopia.

Intacs for keratoconus
At the American Academy of Ophthalmology (AAO) meeting in October 2000, Joseph Colin, MD, offered a research of alternatives to passing through keratoplasty for people with keratoconus. Of 23 eyes in 20 people, 60% achieved a best-corrected visual acuity of 20/40 or much better. The mean postoperative keratometry was decreased by 3 D.

Daniel S. Durrie, MD, discussed Dr. Colin’s paper, which recommends an option that reinforces the already compromised cornea instead of additional thinning it with LASIK. The idea of using an additive procedure, such as Intacs (KeraVision, Fremont, Calif.), to enhance the cornea makes a lot of feeling, Dr. Durrie told Primary Care Optometry Information.

” For several years, we have actually checked out other alternatives to corneal transplants for these people, and also some treatments such as radial keratotomy (RK), photorefractive keratectomy (PRK) or LASIK have actually been tried in the past, yet they get rid of part of the cornea in a client population in which we know the cornea is already thin and weak,” Dr. Durrie claimed.

Due to the fact that the keratoconic eye has a bulge in the cornea, Dr. Durrie said, positioning the Intacs place in the periphery of the cornea will certainly squash the corneal facility. This not just decreases the level of myopia, however strengthens the facility lump, he stated. The wanted outcome is to postpone a corneal transplant for as long as possible.

While the information that Dr. Colin presented program that the procedure is rather secure, stated Dr. Durrie, the longest term information available are only 2 years. “Considering the trends in the 3-month, 6-month as well as 1-year data, it appears that all clients benefited from the procedure, however we can’t claim that it stopped the keratoconus for longer than that till more data are accumulated,” he stated. “Although I remain to do this treatment on separated cases, I tell patients we don’t recognize the lasting results and we don’t understand whether it will certainly reduce, speed up or have no result on the normal course of keratoconus.

” The advantage of this procedure is, if it doesn’t work, you can take the Intacs out as well as have actually not deteriorated the cornea,” he proceeded. “If the individual does need to go on to a corneal transplant, the inserts can be gotten and also not interfere with typical transplant treatment. Due to the adjustment fit of the keratoconic cornea, at some point, individuals become contact lens intolerant, as well as it is necessary to know that there is a different to be examined for these people apart from just referring them for a corneal transplant.”

Specialists should make sure that people comprehend that the treatment is not refractive surgical treatment as well as will not always remedy their nearsightedness, claimed Dr. Durrie. “I have people on whom I have actually performed this procedure who have seen 20/40 without glasses, which would certainly be a superior outcome after a corneal transplant, yet they’re still questioning why their pals that have actually had Intacs implanted can see 20/20 when they can’t,” he stated. “That’s why these people need to be enlightened that this isn’t something that keeps them from using glasses. It maintains them from needing a corneal transplant.”

Hyperopic modification with LTK
photo– Post-LTK: The pulses are applied in eight places, one at the 6-mm area and the various other at the 7-mm area.

Scientific researches have actually shown laser thermokeratoplasty (LTK) to be an effective method of dealing with an individual’s hyperopia, as well as it may additionally hold guarantee for dealing with presbyopia as well as overcorrected nearsightedness after LASIK or PRK, said David J. Conway, OD, supervisor of refractive surgical treatment for Harvard Vanguard Medical Associates in Somerville, Mass

. Dr. Conway reported on the LTK method as well as its outcomes with hyperopia utilizing the Hyperion laser (Daybreak Technologies International, Fremont, Calif.) at the International Society of Refractive Surgical treatment’s Summer World Refractive Surgical Procedure Symposium 2000. Dr. Conway was not associated with any Food and Drug Administration (FDA) research study; his ISRS discussion was based upon details from the Sunrise FDA examinations as well as talks he participated in.

When dealing with a client for hyperopia, the specialist needs to stress the brevity of the treatment, he claimed. “You require to communicate to the person that this is just a temporary modification in his/her hyperopic status,” he said. “There suffices regression with this strategy that the FDA felt it needed to refer this.”

Any kind of procedure for the improvement of hyperopia may demand retreatment with time; this is not one-of-a-kind to LTK, said Sandra Belmont, MD, supervisor of the laser vision facility at the Cornell Weill Medical Facility in New York City City. “Hyperopia enhances as you age,” she said. “We have individuals 3 years out that are stable, so I’m extremely satisfied with the results.”

Dr. Belmont educates patients of this possibility, but none of them have changed their minds. She said that if retreatment were required, people did incline since the procedure is quick, as well as developing a flap, which can lead to difficulties, is not required.

The LTK treatment
picture– Stability: One researcher has individuals that are still steady 3 years post-LTK.

The procedure, Dr. Conway claimed, takes 3 seconds to do. Seven pulses are used in eight areas, twice back to back, one at the 6-mm zone and the other at the 7-mm area. The FDA research study reported that the 612 eyes in 379 people, all older than 40, ranging from +0.75 to +2.50 D, saw no loss in best spectacle-corrected visual acuity (BSCVA) after 2 years, he noted.

” No loss of lines of skill were attributable to the LTK,” he stated. “In comparing preop to 24 months later, there was no loss of BSCVA and also a little bit of gain. We understand that myopes and also hyperopes are really different. Fortunately, the tolerance of hyperopes is extremely practical in making their fulfillment level really high.”

Prior to the procedure, people receive 3 consecutive managements of topical proparacaine at 3-minute periods. Difficulties were minimal, Dr. Conway kept in mind.

” Patients are normally handled from a convenience perspective, strictly with over-the-counter analgesics to obtain them through the very first hrs of recuperation,” he stated. “Because you’re working on the corneal surface, FDA detectives reported a little of foreign-body experience, which dissipates with time extremely perfectly.”

Regression over time
Dr. Conway claimed that, while the patient’s acuity degree remains relatively stable, some regression is evident as the hyperopia boosts gradually. “There will be a little however significant regression in these patients; it’s just an issue of whether it goes to a low sufficient level to validate the individual’s price and also experience of undergoing this method,” he claimed. “By contrasting your cycloplegic to your show refraction, you can inform whether it’s latent hyperopia or not.”

An individual’s age factors in to how much time the impact of LTK might last, said Dr. Conway. “A 50-year-old individual will certainly experience a little extra effect than a 40-year-old individual, possibly because of a bit a lot more dryness or the collagen status of the cornea,” he said.

An off-label indicator of LTK is the therapy of presbyopia, claimed Dr. Belmont. People who are plano and presbyopic might be treated with LTK to accomplish monovision, she said. “Right now, their analysis vision enters into focus,” she stated. “They get their results quickly, and also they’re actually satisfied keeping that.”

Clients that have actually been treated for presbyopia normally will come across the very same level of regression as hyperopes, Dr. Belmont kept in mind. “Presbyopia enhances as you age, as does hyperopia,” she said. “Clients understand that this procedure will need to be improved as their aging demands a boost in the power they’ll require to read. They enjoy as long as you tell them beforehand. I anticipate this as being the treatment to treat farsightedness as well as presbyopia.”

The length of time needed for presbyopic therapy is the same when it comes to that of hyperopia, yet the degree of energy that is related to the eye is varied, she said.

Overcorrected myopia
The procedure may additionally verify to be a valid option for boosting myopic people that have been overcorrected with LASIK or PRK, claimed Dr. Conway. “This qualities a lot of consideration, since you don’t need to eliminate any type of tissue,” he claimed. “Additionally, Daybreak is sending for authorization remediation of presbyopia, making clients short-sighted in a monovision fashion. So, I believe this will come to be a relatively popular and also common option in this person population, and we’ll see the amount of more specialists decide to welcome it.”

LTK is approved for approximately +2.5 D, claimed Dr. Belmont, and is presently undertaking trials for therapy as much as +5.6 D.

Refractec’s conductive keratoplasty
Initial medical tests suggest that conductive keratoplasty (CK) using Refractec’s (Irvine, Calif.) radiofrequency approach is probably secure and efficient for dealing with reduced to modest quantities of hyperopia, according to Penny A. Asbell, MD, that presented clinical trial data in Miami at the International Society of Refractive Surgery meeting. “Very early results with our information bent on twelve month recommend that we get fantastic visual acuity, very good stability as well as actually no negative events, such as loss of vision,” said Dr. Asbell.

CK heats up the stromal tissue with an electric present, shrinks the collagen and also steepens the central cornea, Dr. Asbell explained. A high-frequency existing is used directly right into the peripheral corneal stroma via a shipment pointer placed at eight or more treatment points. The launch of radiofrequency power heats up the surrounding collagen to an uniform temperature level of 65 ° C and also creates a cylindrical impact 500 µm deep vs. a shallower, conical impact made with the LTK method. A cycle of CK-treated spots cinches the cornea and also enhances its curvature to lower hyperopia.

” The change seems to be permanent, and also I think one of the factors that holds true is that the treatment is provided straight to the stroma,” stated Dr. Asbell. “That’s where you desire the result– not on the endothelium, not on the epithelium. It’s a really simple medical method. It’s a non-laser strategy, as well as it includes an additional dimension to what we already can use for refractive surgery– it is an economical treatment,” she included.

CK is consistent
An additional essential issue, Dr. Asbell pointed out, is that CK is a regular therapy. “The therapy dimension and the zone impact in the stroma correspond from treatment spot to therapy area,” she claimed. “One of the key issues to keep in mind is that the temperature level we get with the CK procedure is constantly 65 ° as well as the imprint you make within the peripheral corneal stroma is always the same: 100 µm large and 500 µm deep within the corneal stroma.”

Dr. Asbell is an investigator in the FDA medical trial of CK. Other private investigators at other sites include Marguerite McDonald, MD; Robert K. Maloney, MD; Jonathan Davidorf, MD; Peter Hersh, MD; and Edward E. Manche, MD

. Of the 54 individuals on whom Dr. Asbell reported, the normal age was 55, although, she stated, there is a rather large range old among the trial’s participants. To get approved for the trial, she explained, people had to have uncorrected visual acuity of at least 20/40 or worse and also bad near vision also– conventional for a hyperope. “We are remedying from 1 D to 4 D of hyperopia, with little or no astigmatism,” Dr. Asbell reported.

She stressed the rate and simpleness of the procedure. “This procedure takes 5 mins per eye. It is an extremely brief treatment; you remain in and also out extremely swiftly,” she said. “It is a surgical procedure, yet an extremely easy one. It does not require an experienced specialist [to assist] It doesn’t also need an autoclave. The tip, which has to do with the width of a hair, is non reusable.”

Dr. Asbell explained the CK nomogram because of this: “The therapy is either at 6 mm, 7 mm or 8 mm. You make a mark on the cornea [showing the size of the treatment zone] The level of hyperopia you are dealing with figures out the variety of therapy marks on the cornea. Every one is the same– the exact same amount of power and also the very same deepness within the stroma in each spot,” she stated.

Outcomes show up steady
Of the individuals on whom Dr. Asbell reported, 61% attained uncorrected visual acuity of 20/20 or better 6 months postoperatively and also 96% were 20/40 or far better at the 6-month mark. One year postoperatively, 62% were 20/20 or much better, and 92% were 20/40 or better. “Our outcomes look good as well as stable. These are extremely satisfied people,” said Dr. Asbell. “They actually can return to work instantly or definitely the next day if they so choose. Nobody takes pain medications.”

Safety and security variables were “basically no,” Dr. Asbell reported. “There was no loss of vision and also no corneal edema,” she said. “I think this is mosting likely to be a procedure and also an equipment that’s going to be easy for us to possess and to use and an excellent way to deal with hyperopia postop LASIK or to retouch a postop cataract or corneal transplant,” she said. “I think it’s mosting likely to have a lot of versatility in regards to its uses for dealing with hyperopia and perhaps astigmatism.”

Broadened professional tests of LAPR
SurgiLight Inc. (Orlando, Fla.) has actually expanded its scientific trial researches of laser presbyopia turnaround (LAPR) using its IR-laser in Venezuela, Argentina, Brazil, the Bahamas as well as Japan. Likewise, the company has scheduled installation of the IR-laser in some European countries.

SurgiLight has actually submitted 4 papers to the American Culture of Cataract and also Refractive Surgical Procedure for the May 2001 conference, where more than 500 cases of LAPR will be presented by eye doctors from different nations utilizing the company’s IR laser.

The business remains in the process of getting CE-Mark certification and selecting various international distributors. It plans to submit added 510K applications based upon specific clearances acquired from Premier Laser Systems. SurgiLight anticipates to bill a nobility charge of $500 per individual to doctors who make use of the firm’s IR-3000 system in the USA and Europe.

B&L NuVita phakic IOL
The 3rd generation of George Baikoff, MD’s, anterior chamber phakic IOL is stood for with Bausch & Lomb’s (St. Louis) NuVita MA20. The lens is readily available for myopes ranging from 7 D to 20 D. The style is an angle-fixated, single-piece lens, with a meniscus optical shape and a PMMA surface. The overall optical diameter is 5 mm and also the overall size of the NuVita ranges from 12 mm to 13.5 mm in 0.5-mm increments.

The optic, loophole and footplate were all upgraded from the previous variation to decrease refracted glare, stress in the angle and also much better clearance of the iris as well as natural lens. Additionally, the haptics were revamped to eliminate iris retraction. The haptics were made extra flexible and, therefore, led to much less student ovalization.

In its 2nd generation, the fluorine plasma therapy was added to the manufacturing procedure to create covalent bonds of fluorocarbon radicals with the PMMA surface, which yielded lower surface area power and also incredibly smooth coating. The fluorine treatment significantly enhanced biocompatibility.

In studies performed by Antonio Marinho, MD, with 30-month follow-up, 64% of the 88 eyes dental implanted showed a precision price of ± 0.5 D while 97% showed an accuracy price of ± 2 D. In regards to safety and security, the BSCVA prices had 47 gaining at the very least two lines, and no eyes shed lines. The general glow record revealed that the majority of individuals had couple of issues.

According to Mike Landreville, global supervisor for refractive modern technologies at Bausch & Lomb, the company has no intention of introducing the NuVita lens into the United States for FDA approval or for professional usage. Rather, the firm is developing a whole brand-new phakic innovation for a foldable former chamber phakic lens. The new phakic lens will certainly not only exist as a brand-new lens, however as part of an entirely new system, totally separate from the NuVita line. The brand-new, unrevealed lens system will be of a new material, include a brand-new collapsible delivery system and also supply a new diagnostic tool for implantation.

According to Mr. Landreville, the business plans to have the new system ready for medical use in the USA by this year.

Alcon phakic IOL
A new former chamber phakic IOL existed by Andrew Maxwell, MD, PhD, at the AAO meeting. The lens has an Acrysof-based (Alcon, Ft. Well Worth, Texas) material and has several benefits over various other phakic IOLs such as its foldability, which enables the lens to be inserted via a laceration smaller than 3 mm, as well as an angle-fixated, single-piece style and high biocompatibility. The distance between the cornea and the dental implant likewise drops in between 2.96 mm and also 3.35 mm, a bigger distance than with some other lenses, he claimed.

Dr. Maxwell reported that of the 10 implants that have actually been carried out to day, greater than 90% of the individuals have 20/40 or far better uncorrected vision at their postoperative brows through. The mean round equivalent in people dental implanted thus far was– 11.5 D, he claimed, with an outcome of– 0.39 D at 1 month as well as– 0.8 D at 6 months of residual nearsightedness.

” We see substantial renovation in best-corrected visual acuity, and in all but one individual the postoperative best fixed vision is far better than the very best preoperative vision; in most cases, there are 2-, 3- or 4-line boosts in best-corrected visual acuity,” Dr. Maxwell said. “In the one case where it wasn’t much better, it coincided as the preoperative acuity.”

CIBA gets patents for IOL
CIBA Vision introduced at the AAO meeting that it has obtained 3 licenses from Dr. Baikoff for foldable phakic anterior chamber IOL makes to remedy not just myopia and hyperopia yet also presbyopia.

” We are very excited about this new technology,” David Bailey, surgical service system head of state for CIBA, claimed. “We assume that the MemoryLens product combined with these anterior chamber designs will be a very successful combination.”

That anterior chamber lens effort complements one more refractive implant that was the topic of several discussions in the CIBA Vision booth– the PRL. This posterior-chamber phakic implant is being established by Medennium Inc. CIBA Vision took a 10% equity risk in Medennium in July and also now holds unique around the world marketing as well as distribution legal rights to the lens, which is presently in stage 2 scientific trials.

” We are taking a solid placement in phakic IOLs,” Mr. Bailey claimed, “and we’ll be enhancing that setting with more brand-new modern technology.”
This is the method to deal with myopia, ypermetropia and astigmatism (αστιγματισμος ).

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